1. Field of the Invention
The present invention relates in general to a control apparatus for controlling a machine tool, and more particularly to a control apparatus for a single-purpose machine tool such as a tapping machine, which is not equipped with a complicated numerical controller.
2. Discussion of the Prior Art
For controlling a tapping machine, a drilling unit or other machine tool adapted to perform a comparatively simple machining operation, there has been used a control apparatus using an electronic circuit arrangement as disclosed in laid-open Publication No. 60-44088 of examined Japanese Patent Application. To meet a recent growing need for a complicated machining operation on such a comparatively simple machine tool, the use of a microcomputer for the control apparatus is proposed.
To expand the function of the machine tool to perform the complicated machining operation, however, it is necessary to provide the control apparatus with an increased number of operator's control switches and a sophisticated or large-capacity indicator or display arrangement, resulting in an increased cost of manufacture of the control apparatus.
It is also noted that such a relatively simple machine tool is not always operated by a skilled operator who is familiar with complicated operating procedures. An erroneous manipulation of the control switches may cause an unexpected movement or operation of moving a component or components of the machine tool, which may result in damaging the machine, cutting tool or workpiece.